一般内存拷贝与优化
代码实现
#include<iostream>
usingnamespace
std;
//不安全的内存拷贝(当源内存地址与目标内存地址重叠时会产生错误)
void h_memcpy(void*src,void *dst,intsize){
if (src == NULL|| dst ==
NULL) {
return;
}
const char *s =(char *)src;
char *d = (char*)dst;
while (size--) {
*d++ = *s++;
}
}
//内存移动（安全的内存拷贝，措施为依据源内存地址和目的内存地址不同使用不同的拷贝顺序）
void h_memmove(void*src,void *dst,intsize){
if (src == NULL|| dst ==
NULL) {
return;
}
const char *s =(char *)src;
char *d = (char*)dst;
if (s > d) {
while (size--) {
*d++ = *s++;
}
}elseif(s < d){
// 正向反向拷贝的目的就是为了避免未移动内存被覆盖
d = d + size -1;
s = s +size -
1;
while (size--) {
*d-- = *s--;
}
}
// s == d, you should do nothing!~
}
int main(intargc,const
char* argv[])
{
char s[] = "12345";
char *p1 = s;
char *p2 = s+2;
printf("%s\n",p1);
printf("%s\n",p2);
h_memcpy(p1, p2, 2);
printf("%s\n",p2);
return 0;
}